An artificial grass sports field as generally referred to above is known, for example, see EP 1 158 099.
Many sports, such as field hockey, tennis, American football, etc. are now played on artificial grass sports fields, which fields are made up of an artificial turf as referred to above. Although athletes sustain fewer injuries on a natural grass sports field when falling or making a sliding tackle, on account of the softer surface thereof, such sports fields are often severely damaged when the above sports are played thereon, precisely because they are used intensively and because of the varying influence of the weather conditions.
Artificial grass sports fields, on the other hand, require less maintenance and can be played on much more intensively than natural grass sports fields. To provide artificial grass sports fields with playing characteristics that resemble those of natural grass as much as possible, a granular material such as sand or grains of a synthetic material is spread between the artificial grass fibers. These infilled grains not only provide a softer, shock-absorbing playing surface on which players are less prone to injury, but they also provide improved playing characteristics.
However, the use of an infill in an artificial grass sports field has a number of drawbacks. Not only is the construction of such an artificial grass sports field more labor-intensive than the construction of a natural grass sports field, but an artificial grass sports field provided with an infill requires subsequent maintenance as well. The initially uniform distribution of the granular infill can be disturbed by intensive usage. As a result, areas containing hardly any infill may form in places where the field is played on very intensively, for example in the goal area, which has an adverse effect on the quality of play, but which above all leads to an increased risk of injury. The distribution and the amount of the granular material of an artificial grass sports field provided with an infill must be verified at regular intervals and repairs must be carried out, if necessary.
Furthermore, it has become apparent that the weather influences the properties of the infill with the passage of time, which has a negative effect on the quality of the infill and thus on the playing characteristics of the artificial grass sports field. A negative factor, for example, is the strong compaction of the infill, as a result of which the artificial grass sports field will feel increasingly hard during play, with an increased risk of injury. Furthermore, the synthetic infill may change (harden or become brittle) under the influence of the weather conditions (sunlight, for example). Generally, the currently known artificial grass sports fields that make use of a granular infill are characterized by playing characteristics that deteriorate with the passage of time.